Consumption, digestion, and utilization of beeswax by greater wax moths (Galleria mellonella L.)

Abstract

Greater wax moths (GWM, Galleria mellonella L.) are important pests of Western honey bee (Apis mellifera L.) colonies. The larval moths feed on wax combs, cast honey bee larval skins, pollen, and some honey, leaving behind a destroyed comb containing moth silk and frass. We used standard protocols to determine how GWM larva consumption of wax comb impacts various food utilization and larval growth parameters. Five larval instars (3rd, 4th, 5th, 6th, and 7th) were assessed 24 hours after molting from the prior instar stage and 48 hours before molting to the next instar stage. The consumption rate (CR) of wax was lowest for 3rd instar larvae (17.5 ± 0.8 mg consumed/day, mean ± s.e.) and highest for 7th instar larvae (515.4 ± 22.7 mg/day). The relative growth rate (RGR) was lowest for 7th instar larvae (0.05 ± 0.01 mg/day) and highest in 3rd instar larvae (0.16 ± 0.04 mg/day). A similar trend (decrease in response with increase in larval age) was observed for conversion efficiency of ingested food (ECI), conversion efficiency of digested food (ECD), and approximate digestibility (AD). Third instar larvae had significantly higher ECIs, ECDs, and ADs than did all other larval instars. The data can be used to quantify the efficiency with which the GWM larvae assimilate food and utilize it for growth.